Improvement in pulley-blocks



UiTTTED STATES PATENT QFFIoE.

ROBERT MARSDEN, OF SHEFFIELI), ENGLAND.

IMPROVEMENT EN PEJLLEVBLOCKS.

Specilication forming part of Letters Patent No. 116,613, dated July 4, 1871.

To all whom t may concern.-

Be it known that I, ROBERT MAnsDnN, of Sheffield, in the county of York, England, have invented certain new and useful Improvements in Pulley-Blocks for Raisingl Heavy Weights; and I do hereby declare that the following is a full, clear, and exact description thereof, reference being had to the accompanying drawing making part of this sliecification.

I make use of the well-known principle ofthe endless screw or worm and worm-wheel, and, by a novel arragement of parts, I make them applicable to the purposes for which pulley-blocks are ordinarily used-that is, for the purpose of mov ing or raising heavy weights; then I make, by casting in malleable or castiron or other metal, a wornrwheel ofthe size I require, and then, by cutting or casting, make a worm or endless screw to correspond with and work into such wheel. I then make, either in ast or malleable iron, or by iorging, a frame, which shall contain the hook from which the whole is to be suspended and likewise the above worm and wheel, the worm being carried in suitable bearings either in the top or bottom ot' the frame, and the axis oi' the. wornrwheel in bearings in the side cheeks thereof. I then make a small east-iron pulley to carry the litting-chain, which is made to run freely on. its axle, which is also the axle of the wormwhcel, and which gears into the above wormwheel by means of clutches cast onto the faces oli' the said wheel and pulley respectively. The clutches are forced together by means of a spring iixcd to one of the side cheeks ot" the frame. On the sides ot' the frame mentioned above I place a small bent lever, which, acting on the chainpulley, compresses the spring and draws the pulley out ot' gear, by which the chain runs freely, and can be at once adjusted to its work. I then attach either a chain or sprocket-wheel or ropewheel, over which a hand-chain or rope is worked, to the end otl the spindle, upon which the worm is placed, and the whole of the parts are then complete.

In order that my said invention may be more fully understood and readily carried into eiiect, l will proceed to describe the drawing hereto annexed.

Figure l is a side view of a pulley-block constructed accordingto my invention.

A A is the frame, and B the hook by which it is suspended. G, an axis carried by the frame, and having upon it the worm D and the handchain wheel E. F is a hand-chain passing over the wheel E, and by it the axis C is rotated to raise and lower the weight. G is an axis carried by the cheeks of the frame, and having lixed upon it. the worin-wheel H, which gears with the worm l). l is a chain-wheel to receive the lifting-chain l; it is mounted loosely on the axis G, and is pressed toward the worm-wheel H by the spring L. rlhe wheels H and I have clutching projections upon them., so that when the wheel H revolves it carries the wheel I with it. These projections are clearly shown in Figs. 2 and 3, which are side views oit' the wheels II and I respectively. The projections are somewhat inclined, so that the strain on the lifting-chain has a tendency to hold the parts ofthe clutch together. M is a lever with a cord, N, attached to it. By pulling this cord the wheel I is drawn out of gear with the wheel H, and then the wheel I is able to turn i'reely to allow the lifting-chain to be adjusted to its work without loss ot' time.

llavin g thus fully described the nature oi' my invention and the manner in which it is to be carried into eli'ect, I wish it to be understood that l. claim as my inventionl. The ira-nie, as shown in the drawing and described in the above specification, in which the hook for suspending the same and the other working parts are contained.

2. The combining together the worm-wheel and the chainpulley by means of clutches, by which they can he geared or ungeared into each other as occasion may require.

ROBT. MARSDEN.

lith esses F. F. Hrnnnn'r, G. L. HARVEY. 

